Instrument for transmitting ultraviolet radiation to a limited area

ABSTRACT

AN INSTRUMENT FOR TRANSMITTING ULTRAVIOLET RADIATION TO A LIMITED AREA WITHIN A CONFINED SPACE, SUCH AS A DENTAL INSTRUMENT FOR TREATING A LIMITED AREA WITHIN THE HUMAN MOUTH. THE INSTRUMENT IS HAND-HELD AND INCLUDES A SUPPORT ON WHICH A SOURCE OF ULTRAVIOLET LIGHT IS MOUNTED. AN ELONGATED LIGHT-DIRECTING STRUCTURE IS CARRIED BY THE SUPPORT AND EXTENDS FROM THE LIGHT SOURCE BEYOND THE SUPPORT SO AS TO HAVE A FREE END WHICH MAY BE PLACED IN THE MOUTH FOR DIRECTING THE LIGHT TO A LIMITED AREA FOR APPLYING ULTRAVIOLET ENERGY THERETO. A MANUALLY OPEABLE CONTROL IS PROVIDED TO BE MANIPULATED BY THE OPERATOR FOR CONTROLLING THE TRANSMISSION LIGHT AND THUS CONTROLLING THE APPLICATION OF ULTRAVIOLET ENERGY.

Jan. 23 1973 o. E. LIENHARD INSTRUMENT FOR TRANSMITTING ULTRAVIOLET RADIATION TO A LIMITED AREA 5 Sheets-Sheet 1 Filed March 15, 1971 INVENTOR 47m 5 .Z/EA/HAWD Thqi.

Jan. 23, 1973 o. E. LIENHARD INSTRUMENT FOR TRANSMITTING ULTRAVIOLET RADIATION TO A LIMITED AREA 5 Sheets-Sheet 2 Filed March 15, 1971 l/Y/YI/ 'ATTORN EYS 1973 o. E. LIENHARD 3,712,984

INSTRUMENT FOR TRANSMITTING ULTRAVIOLET RADIATION TO A LIMITED AREA Filed March 15, 1971 5 Sheets-Sheet 3 ATTORNEYS JUL 1973 o. E. LIENHARD 3,712,984

INSTRUMENT FOR TRANSMITTING ULTRAVIOLET RADIATION TO A LIMITED AREA INVENTOR firm t. baa/42.0

@240, MM Y ATTORN EYS Jan. 23, 1973 o. E. LIENHARD 3,712,934

INSTRUMENT FOR TRANSMITTING ULTRAVIOLET RADIATION TO A LIMITED AREA Filed March 15, 1971 5 Sheets-Sheet 5 P W l *s d I ,q" i

i N l J. 'INVENTOR drmfl/fA/flflip ATTORN EYS United States Patent 3,712,984 INSTRUMENT FOR TRANSMITTING ULTRA- VIOLET RADIATION TO A LIMITED AREA Otto E. Lienhard, Upper Montclair, N.J., assignor to Cant-ad Precision Industries, Inc. Filed Mar. 15, 1971, Ser. No. 124,084 Int. Cl. Htllj 37/00 US. Cl. 250--86 41 Claims ABSTRACT OF THE DISCLOSURE An instrument for transmitting ultraviolet radiation to a limited area within a confined space, such as a dental instrument for treating a limited area within the human mouth. The instrument is hand-held and includes a sup port on which a source of ultraviolet light is mounted. An elongated lightdirecting structure is carried by the support and extends from the light source beyond the support so as to have a free end which may be placed in the mouth for directing the light to a limited area for applying ultraviolet energy thereto. A manually operable control is provided to be manipulated by the operator for controlling the transmission of light and thus controlling the application of ultraviolet energy.

BACKGROUND OF THE INVENTION The present invention relates to instruments for directing ultraviolet radiation to a limited area which is situated in a confined space.

Thus, the present invention is particularly applicable to a dental instrument to be used for applying ultraviolet radiation to a limited area within the mouth.

In recent times considerable advances have been made in the development of protection against caries, particularly in children, by applying a sealant to the teeth and curing the sealant so that it hardens to provide a protective cover which seals pits and fissures. The sealant has the property of hardening when exposed to ultraviolet light. Thus, the sealant may take the form of an adhesive which is relatively stable, thick liquid containing as its major ingredients 3 parts by Weight of the reaction product of bisphenol A and glycidyl methacrylate, and 1 part by weight of methyl methacrylate monomer. Just before use 2.0% of benzoin methyl ether is dissolved in the adhesive liquid so as to form an ultraviolet light-sensitive composition which is painted onto the tooth surface with a fine camels hair brush. The teeth can be preliminarily conditioned for receiving the sealant. After the sealant is applied it is exposed to longwave ultraviolet light for a period of from to 30 seconds, which cures and hardens the sealant. Thus, development of cavities is prevented by the adhesive sealant which protects the chewing surfaces of the teeth against cavity-causing food particles and harmful bacteria in the mouth. The protective sealant has been particularly successful with back teeth at pits and fissures on the biting surfaces thereof where such teeth are particularly prone to decay.

One of the particular problems encountered with this latter type of treatment is the development of an instrument suitable for exposing the sealant to ultraviolet light. Thus, it is necessary to confine the ultraviolet radiation to the limited area to which the sealant is applied, and this limited area itself is situated in a confined space formed by the interior of the human mouth. The individual who carries out the treatment must have an instrument which will permit the required ultraviolet radiation to be applied precisely to the relatively confined area where the sealant is situated. Because the sealant responds to ultraviolet light it is necessary to direct such light from a suitable source to the confined area, and this requirement has created problems with respect to maintaining parts cool as well as limiting the radiation to a desired wavelength range.

Furthermore, it is of course highly desirable to be able to provide an instrument which can be comfortably manipulated by a dentist, for example, in such a way as to rapidly and conveniently carry out the desired treatment with a minimum amount of discomfort to the patient as well as the operator of the instrument.

Furthermore, it is highly desirable to be able to keep the costs of the instrument low enough to make it feasible for the instrument to be widely used.

SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide an instrument which will fullfill the above requirements.

Thus, it is an object of the present invention to provide a relatively simple, inexpensive instrument, which can conveniently be held in one hand of the opera'or and which at the same time is capable of precisely directing ultraviolet light of a selected range of wavelengths to a relatively limited area in a confined space such as to the area of the back teeth in the interior of a human mouth.

It is a further object of the present invention to pro vide an instrument of the above type which will reliably remain in a relatively cool condition while at the same time having safety features which will prevent overheating of the instrument.

Also it is an object of the present invention to provide an instrument of the above type which is of a relatively light weight and which can be accommodated in a relatively small space while at the same time being capable of providing the power which is required for energizing of the ultraviolet source.

The object of the present invention also includes the provision of a structure which will enable the operator to control in a very precise manner the transmission of the ultraviolet radiation.

According to the invention the instrument includes a handle means to be held in the hand of the operator and a support means which is carried by the handle means. This support means supports a source of ultraviolet light. A light-directing means. is carried] by the support means and extends from the source beyond the support means where the light-directing means terminates in an elongated free end portion adapted to be introduced into the mouth. This light-directing means serves to direct the ultraviolet light from the source to the area which is to receive the ultraviolet energy. A manually operable control means is carried by the support means at the region of the handle means so as to be accessible to the hand of the operator which holds the handle means. This control means coacts with the light-directing means for controlling the transmission of ultraviolet light thereby.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a simplified perspective illustration of an embodiment of an instrument according to the invention, the instrument being shown in FIG. 1 in the position it takes when it is not used;

FIG. 2 illustrates how the hand-held part of the instrument is raised from the base thereof when the instrument is to be used;

FIG. 3 is a longitudinal sectional elevation of the handheld part of the instrument;

FIG. 4 is an exploded perspective illustration of the optical components of the instrument;

FIG. 5 is a fragmentary sectional plan view, taken along line 5-5 of FIG. 3 in the direction of the arrows, and illustrating the manually-operable control means of the instrument;

FIG. 6 is a sectional plan view taken along line 6-6 of FIG. 3 in the direction of the arrows and showing in greater detail the manner in which components, particularly optical components, are mounted in the hand-held part of the instrument;

FIG. 7 is a transverse sectional elevation taken along line 77 of FIG. 1 in the direction of the arrows and showing details of the base means and the hand-held part resting thereon, FIG. 7 showing in particular the manner in which cooling air is supplied and also showing part of the power supply structure; and

FIG. 8 is a wiring diagram.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring first to FIG. 3, the instrument of the invention includes a hand-held part 10. This part 10 includes a handle means 12 capable of being held in the hand of the operator in a manner similar to the handle of a gun. As is apparent from FIG. 3 the entire hand-held struc ture illustrated therein has the general configuration of a gun, in fact, the entire structure of FIG. 3 may be considered as a gun for transmitting ultraviolet light.

The handle means 12 carries a support means 14 in the form of a hollow housing. Thus, these components 12 and 14 may be integrally molded of a suitable plastic. For example the handle 12 and housing 14 may initially have the form of a pair of hollow halves which are placed together to define the interior of the handle means 12 and the interior of the housing 14, these interiors directly communicating with each other. The right end of the housing 14 is closed by a suitable closure element 16, as viewed in FIG. 3. At its left end, as viewed in FIG. 3, the housing 14 is closed by a cap assembly 18 made up of a pair of plastic closure halves connected to and closing the left end of the housing 14 and coacting to form an elongated tubular connecting member 20 which is threaded at its exterior. The threaded tubular part 20 communicates at its right end with the interior of the housing 14. This part 20 integrally carries a plurality of elongated gripping jaws 22 which are capable of resiliently moving toward and away from the axis of the tubular part 20 and which are distributed about this axis so as to form a structure similar to the jaws of a collet chuck.

The pair of plastic elements which form the closure 18 are held together by a plastic ring 24 which may have a bay netype of connection with the parts which form the closure 18. The threaded tubular part 20 receives an internally threaded gripping member 26 which is threaded onto the tubular part 20 and which has an inner tapered surface coacting with the jaws 22 so as to press them inwardly to grip, in a releasable manner, an elongated rod 28 which forms part of the light-directing means of the instrument of the invention.

The elongated rod 28 forms part of the elongated lightdirecting means and is in the form of a quartz rod forming a light pipe for conveying the ultraviolet light along the interior of the rod 28 so that it can issue from the end 30 thereof. The left end of the rod 28, as viewed in FIG. 3, may be curved as illustrated, but by removing the gripping nut 26 of the chuck it is possible to remove one rod 28 and replace it with another rod. Thus it is possible to use in the instrument any one of a number of differently shaped rods 28. These rods may have different lengths and may have free ends of different curvatures and also of different lengths, so that it is a simple matter to use a rod 28 which is particularly suited for a given patient and for a given purpose.

When the pair of plastic elements which form the closure 18 and the tublar part 20 are assembled, they receive in an internal groove formed at the right end of the closure 18, as viewed in FIG. 3, a filter 32, and it will be noted that the right end of the rod 28 is located in close proximity to the filter 32. Thus the elements of assembly 18 are held together by the ring 24 while the rod 28 is held by the gripping nut 26 which presses the jaws 22 of the chuck against the exterior of the rod 28.

The light which is directed along the interior of the rod 28 is derived from a source 34 of ultraviolet light. This is a conventional ultraviolet light source which becomes energized when a circuit in which it is located is closed. Thus, the source 34 of ultraviolet light is connected through suitable leads 36 to a power supply in a manner described in greater detail below.

The ultraviolet light source 34 will provide light over range of wavelengths which will include shorter wavelengths which are not desired. Thus, for the particular application of curing of an adhesive sealant in the mouth of a patient, as described above, wavelengths under 3200 A. are undesired. The properties of the filter 32 are such that it will absorb these undesirable wavelengths and thus enable the light-directing means to transmit at least 60% of radiation at 3600 A and at longer wavelengths, and to absorb at least of wavelengths in the band from 5000 to 6000 A.

Between the source 34 and the rod 28 the light-directing means includes a condenser in the form of an elongated cylindrical body 38 which also may be made of quartz. Thus it is this condenser 38 which receives the light directly from the source 34 and transmits it to the rod 28. It is to be noted that instead of using a filter it is possible to provide components 28 and 38 the properties of which are such that they will absorb the undesired wavelengths, but

it is preferred for reasons of simplicity and low cost to use the filter 32.

A gap 40 is defined between the filter 32 and the condenser 38. A manually operable control means 42 of the invention operates in the gap 40 for controlling the transmission of light. The manually operable control means 42 includes a swingable trigger member 44 accessible to the hand which holds the handle means 12. This trigger member 44 is in the form of an elongated plate formed from any suitable plastic, which may be the same material as that used for the housing 14 as well as the assembly 18 and the elements 24 and 26 and the closure cap 16. The swingable trigger member 44 is fixed to a relatively short shaft 46 which is journaled in a bearing 48 formed by the assembled halves of the housing 14. Above the bearing 48 the shaft 46 is fixed with an elongated lever 50 which at its left end, as viewed in FIG. 3, carries the substantially L-Shaped light-blocking element 52. This element 52 may be formed of a suitable metal, for example, and it is opaque so that the light cannot travel therethrough. The blocking element 52 is swung into the gap 40 in order to block the transmission of light and out of the gap 40 in order to continue the transmission of light from the condenser 38 to the filter 32 and the rod 28.

As is shown most clearly in FIG. 5, the bottom wall of the housing 14 carries a pair of lateral ribs 54 which extend beneath the lever 50. The lever 50 has at its lower surface a stop projection 56 situated between the free ends of the transverse ribs 54. Thus the lever 50 may be swung between the solid and dot-dash line positions indicated in FIG. 5. In the dot-dash line position the light-blocking element 52 is situated beyond the gap 40 so that the light is not blocked while in the solid line position of FIG. the light-blocking element of the manually operable control means 42 is situated in the gap preventing transmis sion of radiation from the condenser 38 to the filter 32. Thus the inner free ends of the ribs 54 which define the gap which accommodates the projection 56 form stops which limit the swinging of the lever 50 by the trigger element 44. At the right of the shaft 46, as viewed in FIG. 5, the lever 50 has a substantially pointed free end portion 58 which frictionally presses against an elongated curved spring element 60. This spring element 60 is of a generally U-shaped configuration and has a pair of inwardly extending ears 62 formed with openings receiving mounting screws 64. These screws 64 serve to mount the spring 60 on the lower surface of an interior mounting assembly 66 which is situated within the housing 14.

The mounting assembly 66 has an elongated wall 68 extending longitudinally along the interior of the housing 14 adjacent a wall 70 thereof. The wall 70 of the housing 14 integrally carries a plurality of bosses 72 which are integrally molded with the housing and one of which is illustrated in FIG. 6. Suitable bolts 74 extend through openings of the wall 68 into threaded bores of the bosses 72 for supporting the mounting assembly 66 in the interior of the housing 14. The mounting assembly 66 includes components 76 for supporting the condenser 38. Also the mounting assembly 66 includes a socket 78 for the light source 34. The interior mounting assembly 66 may be made of aluminum and forms in effect an interior housing for enclosing the light source 34 and the inner end of the condenser 38. The parts which form the mounting assembly 66 are held together by a nut 80 carried by a screw 82 fixed to projecting from the wall 68. This screw 82 passes through an opening in a cover 84 which is held assembled with the other parts by the nut 80 and serves to hold all of the components with the mounting assembly 66 together.

FIG. 6 illustrates the blocking element 52. It is indicated in FIG. 6 in solid lines in its blocking position and in dot-dash lines in its non-blocking position. The leads 36 extend through a suitable opening in the cover 84 of the mounting assembly 66.

Also, it is to be noted that the bottom wall of the mounting assembly 66 carries an elongated shaft '86 which extends into the hollow shaft 46. The components of the mounting assembly 66 may be made of aluminum or other metal which has a good heat-conducting capability.

The trigger element 44 may be formed integrally with the hollow shaft 46 and the lever 50 so as to be guided at the shaft portion 46 not only by the exterior bearing 48 but also internally by the shaft 86 which is threaded into a threaded bore formed in the bottom wall of the inner housing of the mounting assembly 66 and which is held in position by a lock nut 88.

The wall 70 of the housing 14 as well as the opposite wall 90 (FIG. 7) are formed with elongated apertures 92 which extend longitudinally along the housing 14 over substantially more than one-half the length the entire housing 14, so that through these apertures it is possible for cooling air to flow transversely across the interior of the housing 14.

Suitable ribs in the interior of the handle means 12 and housing 14- support a thermally responsive switch 94 there in. This switch 94 communicates directly with the interior of the housing 14 at the junction between the latter and the handle means 12. This switch 94 is of a known construction which is capable of responding to reaching of a given temperature for assuming automatically an open position, while below this temperature the switch remains in its normally closed position. The leads 36 from the light source 34 extend to a plug 96 which receives the prongs of a second plug 98. These plugs are suitably mounted in the interior of the handle means 12. The leads a and 100!) of the pronged plug 98 extend respectively to the switch 94 and the power-supply cable 102. This cable includes a conductor 100a which goes directly to the switch 94. A third conductor 100d of the power cord 10?. forms a ground connection for safety purposes. Thus the thermally responsive switch 94 is connected in series with the light source 34 so as to automatically extinguish the latter when the temperature within the housing 14 rises to a predetermined value.

The power supply cord 102 extends to the exterior of the handle means 12, at the bottom end thereof, as indicated in FIG. 3, and this cord is connected to a suitable power source as described below.

Referring to FIG. 1 it will be seen that when the hand held part 10 of the instrument of the invention is not used it rests on a base means 104. When the instrument is to be used the hand-held part 10 is raised from the base means 104, as indicated in FIG. 2. Thus, FIG. 2 illustrates a recess 106 which receives the housing 14. This recess 106 includes a wall portion 108 of the base means 104, and this wall portion is itself formed with elongated apertures 110.

As is clearly apparent from PEG. 7, the elongated apertures 110 of the recess 106 become aligned with the apertures 92 of the wall 70. Situated within the hollow base means 104 is a blower or fan 112 driven by a motor 114. The motor 114 together with the blower or fan 112 are mounted in any suitable way within the hollow base means 104 so as to direct cooling air upwardly through the apertures 110 and then across the interior of the housing 14 through the apertures 92. Thus the entire handheld part can be effectively cooled while it rests on the base means 104.

The base means 104 is thus itself in the form of a hollow housing, and it accommodates in its interior various components of the power supply assembly. The power may be delivered to the entire instrument through a cord 116 which can have a suitable plug to be introduced into any suitable wall outlet, for example. A recessed portion 118 of the base means is provided with a pronged element to receive a cooperating plug element 120 located at the free end of the power supply cord 102.

Also, the hollow base 104 has a raised wall portion 122 formed with openings 124 through which cooling air can enter so as to flow over the motor 114 and be delivered by the blower 112 upwardly through the apertures 110. The base means 104 includes a peripheral sidewall on which is mounted the top wall which supports the part 10 of the instrument as well as the plug which receives the element 120. It is this top wall which has the portion 122 formed with the apertures 124. Also, the peripheral wall is fixed with a bottom wall 126 (FIG. 7) carrying suitable feet 128 which may be provided with pads 130 so that there is suflicient clearance for the cord 116 to extend beneath the base means 104.

The electrical circuit of the instrument of the invention is illustrated in FIG. 8 where the base means 104 is schematically represented as one unit for accommodating the power supply assembly in its interior while the hand-held part 10 is schematically represented as a second unit which carries the electrical components of this part of the instrument. The elements of FIG. 8 which correspond to those described above are indicated by the same reference characters. The power supply cable 116 has one conductor 100d which is grounded, as pointed out above. The conductors and 1000 are connected to a transformer 132 mounted in the interior of the base means 104. This transformer has various taps which may be selected by a voltage tap-changer 134. One of the conductors of the supply cable 116 is provided with a fuse 136 connected in series with a master switch 138 which is depressed to be turned on and again depressed to be turned off in a well known manner. The circuit also includes a pilot lamp 140 which when illuminated will indicate that the instrument is turned on. The switch 138 may be situated at the front part of the base means 104, as illustrated in FIGS. 1 and 2, and a depressible element thereof may be transparent to glow when the lamp 140 is illuminated.

Thus, with the above-described relatively simple structure it is possible to direct in a precisely controlled manner ultraviolet radiation to a limited area in a confined space. The quartz rod 28 may be readily introduced into the mouth of the patient so that the radiation issuing from the end region 30 thereof can supply the required ultra violet radiation to the desired area.

In order to use the instrument the operator will simply close the switch 138. This will cause the motor 114 to operate continuously and it will also cause the lamp 34 to be energized. The transmission of ultraviolet light is simply blocked and unblocked by the manipulation of the manually operable means 42. The hand-held part is effectively cooled while it rests on the base means 104, but it is also cooled during operation because of the capability for the air to flow freely through the apertures 92 even when the part 10 is displaced away from the base means 104. It is to be noted that if the switch 94 opens the extinguishing of the lamp 34 will result in rapid cooling so that the switch 94 will quickly close again to reestablish the circuit. The part 10 is very light and easily handled and manipulated with one hand of the operator. Also the base means 104 is relatively small and can easily be accommodated on the surface of a suitable table, desk, or the like.

Because of the simplicity of the structure and the reliability with which it operates there is almost never any need for maintenance, but if replacement of parts or the like is required the structure lends itself to rapid disassem bly and reassembly so that such replacement of parts can be carried out very expeditiously.

What is claimed is:

1. In an instrument for transmitting ultraviolet radiation to a limited area in a confined space such as the interior of a human mouth, handle means to be held in the hand of an operator of the instrument, support means carried by said handle means, an ultraviolet light source carried by said support means, elongated light-directing means carried by said support means and extending from said source beyond said support means to be introduced into the confined space for directing ultraviolet light to the limited area, said light directing means including an elongated light directing rod formed of a light pipe for conveying light along the interior of said rod and issuing the light from a free end portion of the rod distant from said support means, a condenser situated between said light source and said rod, and a gap between said rod and said light source; and manually operable control means carried by said support means for controlling the transmission of light by said light-directing means, said control means including a light blocking means displaceable into and out of said gap and therefore the path of light in said light-directing means While said light source is maintained on to respectively block and clear said path of light, trigger means positioned adjacent said handle means so as to be displaceable by a finger of the operators hand holding said handle means, and swingable lever means carrying said light blocking means and connected with 8 said trigger means for swinging movement therewith to displace said light blocking means in response to the manual manipulation of said trigger means.

2. The combination of claim 1 and wherein said lightdirecting means coacts with said source for transmitting only light within a selected range of wavelengths therefrom.

3. The combination of claim 2 and wherein said lightdirecting means coacts with said source for absorbing relatively short wavelengths while transmitting longer wave-lengths.

4. The combination of claim 3 and wherein said lightdirecting means coacts with said light source for absorbing short wavelengths which are under 3200 A. While transmitting at least 60% of radiation at 3600 A. as well as longer wavelengths.

5. The combination of claim 4 and wherein said lightdirecting means coacts with said light source for further absorbing at least of wavelengths in the band from 5000 to 6000 A.

6. The combination of claim 1 and wherein said rod is made of quartz.

7. The combination of claim 1 and wherein said lightdirecting means includes a filter situated at an end of said rod which is directed toward said light source for trans mitting through said rod only light within a selected wavelength range.

8. The combination of claim 1 and wherein said lever has a free substantially pointed end portion terminating in a tip, and a spring frictionally engaging said tip during swinging of said lever by said trigger means.

9. The combination of claim 6 and wherein said condenser is made of quartz.

10. The combination of claim 1 and wherein said condenser and rod are spaced from each other so that said gap is defined therebetween.

11. The combination of claim 1 and wherein said support means includes a housing formed with apertures through which cooling air can pass for cooling the interior of said housing, said source as well as part of said lightdirecting means and part of said control means being located within said housing of said support means to be cooled by air flowing through said apertures of said housing.

12. The combination of claim 11 and wherein an electrical means is carried by said support means and operatively connected with said source for energizing the latter from a power supply, and said electrical means including a safety switch for automatically opening the circuit to said source when a given temperature is reached at the region of said safety switch, said safety switch being lo cated in a space whose temperature corresponds to that in the interior of said housing.

13. The combination of claim 11 and wherein a base supports said housing and the parts carried thereby when the instrument is not used.

14. The combination of claim 13 and wherein a power supply is carried by said base for supplying power for energizing said light source.

15. The combination of claim 11 and wherein said support means includes a housing formed with apertures through which cooling air can pass for cooling the interior of said housing, said source as well as part of said light-detecting means and part of said control means being located within said housing to be cooled by air flowing through said apertures of said housing, and wherein a base supports said housing and the parts carried thereby when the instrument is not used, said base having a wall formed with apertures communicating with the apertures of said housing when the latter is on said base, and including a blower carried by said base at the side of said wall opposite from said housing for blowing cooling air through the apertures of said wall and the apertures of said housing for cooling the interior of the latter.

16. -In an instrument for transmitting ultraviolet radiation to a limited area in a confined space such as the interior of a human mouth, handle means to be held in the hand of an operator of the instrument; support means carried by said handle means and including a housing formed with apertures through which cooling air can pass for cooling the interior of said housing; a heat generating ultraviolet light source carried by said support means; elongated light-directing means carried by said support means to be introduced into the limited area; said source means as well as part of said light-directing means being located within said housing to be cooled by air flowing through said housing apertures; a base for supporting said housing and the parts carried thereby when the instrument is not used having a wall formed with apertures communicating with said housing apertures when said housing is on said base; and a blower carried by said base and positioned to blow cooling air through the apertures of said base wall and said housing apertures for cooling the interior of said housing.

17. The combination of claim 16 and wherein a power supply is carried by said base for supplying power for energizing said light source.

18. The combination of claim 16 and wherein said light-directing means coacts with said source for transmitting only light within a selected range of wavelengths therefrom.

19. The combination of claim 18 and wherein said light-directing means coacts with said source for absorbing relatively short wavelengths while transmitting longer wavelengths.

20. The combination of claim 19 and wherein said light-directing means coacts with said light source for absorbing short wavelengths which are under 3200 A. while transmitting at least 60% of radiation at 3600 A. as well as longer wavelengths.

21. The combination of claim 20' and wherein said light-directing means coacts with said light source for further absorbing at least 90% of wavelengths in the band from 5000 to 600 A.

22. The combination of claim 16 and wherein said light-directing means includes an elongated light-directing rod forming a light pipe for conveying light along the interior of said rod and issuing the light from a free end portion of the rod distant from said support means.

23. The combination of claim 22 and wherein said rod is made of quartz.

24. The combination of claim 22 and wherein said light-directing means includes a filter situated at an end of said rod which is directed toward said light source for transmitting through said rod only light within a selected wavelength range.

25. The combination of claim 24 and wherein a condenser forms part of said light-directing means and is situated adjacent said light source between the latter and said filter.

26. The combination of claim 25 and wherein said condenser is made of quartz.

27. The combination of claim 25 and wherein said condenser and rod are spaced from each other so that light travels through a gap between said condenser and rod of said light-directing means, and including lightcontrolling means including a light-blocking means displaceable into and out of said gap in said light directing means while said light source is maintained on for respectively preventing and permitting transmission of light from said condenser to said rod.

28. The combination of claim 27 and wherein said control means includes a swingable trigger means operatively connected with said light-blocking member for swinging the latter into and out of said gap.

29. The combination of claim 28 and wherein a swingable lever carries said light-blocking member and is connected with said trigger means for swinging movement therewith, said lever having a free substantially pointed 10 end portion terminating in a tip, and a spring frictionally engaging said tip during swinging of said lever by said trigger means.

30. In an instrument for transmitting ultraviolet radiation to a limited area in a confined space such as the interior of a human mouth, handle means to be held in the hand of an operator of the instrument; support means carried by said handle means, an ultraviolet light source carried by said support means; elongated light-directing means carried by said support means and extending from said source beyond said support means to be introduced into the confined space for directing ultraviolet light to the limited area, said light-directing means including an elongated quartz light-directing rod forming a light pipe for conveying light along the interior of said rod and issuing the light from a free end portion of the rod distant from said support means, and a separate filter intermediate said rod and said source for transmitting through said rod only light within a selected wavelength range, said support means including means for releasably supporting said rod for the separate removal of said rod from said support means and manually operable control means carried by said support means for controlling the transmission of light by said light-directing means, said control means including a light blocking means displaceable into and out of the path of light in said light directing means while said light source is maintained onto respectively block and clear said path of light.

31. The combination of claim 30 and wherein said filter absorbs relatively short wavelengths while transmitting larger Wavelengths.

32. The combination of claim 31 and wherein said filter absorbs short Wavelengths which are under 3200* A. while transmitting at least 60% of radiation at 3600 A. as well as larger wavelengths.

33. The combination of claim 32 and wherein said filter also absorbs at least of wavelengths in the hand from 5000 to 6000 A.

34. The combination of claim 30 and wherein a condenser forms part of said light-directing means and is situated adjacent said light source between the latter and said filter.

35. The combination of claim 34 and wherein said condenser is made of quartz.

36. The combination of claim 30 and wherein said condenser and rod are spaced from each other so that light travels through a gap between said condenser and rod of said light-directing means, said light-blocking means displaceable into and out of said gap in said light directing means while said light source is maintained on for respectively preventing and permitting transmission of light from said condenser to said rod.

37. The combination of claim 3-6 and wherein said control means includes a swingable trigger means operatively connected with said light-blocking member for swinging the latter into and out of said gap.

38. The combination of claim 37 and wherein a swingable lever carries said light-blocking member and is connected with said trigger means for swinging movement therewith, said lever having a free substantially pointed end portion terminating in a tip, and a spring frictionally engaging said tip during swinging of said lever by said trigger means.

39. The combination of claim 30 and wherein said support means includes a housing formed with apertures through which cooling air can pass for cooling the interior of said housing, said source as well as part of said lightdetecting means and part of said control means being located within said housing to be cooled by air flowing through said apertures of said housing, and wherein a base supports said housing and the parts carried thereby when the instrument is not used, said base having a wall formed with apertures communicating with the apertures of said housing when the latter is on said base, and including a blower carried by said base at the side of said wall opposite from said housing for blowing cooling air through the apertures of said Wall and the apertures of said housing for cooling the interior of the latter.

40. The combination of claim 30 and wherein a base supports said housing and the parts carried thereby when the instrument is not used.

41. The combination of claim '40 and wherein a power supply is carried by said base for supplying power for energizing said light source.

References Cited UNITED STATES PATENTS 2,227,422 1/1941 Boerstler 350% R 5 1,800,277 4/1931 Boerstler 35096 R 1,677,016 7/1928 Berry 128397 3,261,978 7/1966 Brenman 25086 JAMES W. LAWRENCE, Primary Examiner 10 C. E. CHURCH, Assistant Examiner U.S. Cl. X.R. 350-96R 

